The present invention relates to an oxygen absorber. More particularly, the present invention relates to a composition of an oxygen absorber with improved oxygen absorption performance.
An oxygen absorber is a material capable of absorbing oxygen from surrounding atmosphere. Conventionally, the oxygen absorber has been used for protecting packaged foods and other products against spoilage, mold growth, color change, rancidity, loss of a nutritive value, insect damage and loss of quality. The oxygen absorber has been also used for protecting a metal product against corrosion, an antique wood against deterioration, a chemical and drug against oxidation, and so on.
The oxygen absorber has been produced in a variety of forms such as a packet form, powder, a pellet, a sheet and a tablet according to applications thereof. When the oxygen absorber is retained in a sealed packaging of food, the oxygen absorber absorbs oxygen inside the sealed packaging and maintains the oxygen content at a low level.
In the food storage industry, the use of the oxygen absorber has been critical for increasing a storage life of foods for a long-term storage. There have been two types of oxygen absorbers used for the storage of food. The first type requires moisture from surrounding atmosphere or food to perform the absorption. The second type contains moisture and is suitable for dry pack canning with low moisture. The first type works slower as the oxygen absorber must first absorb moisture before absorbing any oxygen. Because the second type contains moisture, the oxygen absorber starts absorbing oxygen immediately and tends to last a shorter period of time as compared with the first type. These characteristics are selected according to the applications.
The oxygen absorber performs the oxygen absorbing action through a chemical reaction as follows:

A typical conventional oxygen absorber contains iron powder, and the iron powder reacts with oxygen in the surrounding atmosphere, thereby causing the iron powder to rust. When a surface of the iron powder has oxidized, the absorbing action stops. Therefore, it is necessary to use fine iron powder with a large surface area to absorb a large quantity of oxygen.
In order to promote the reaction of the iron, it is sometimes tried to add an electrolyte such as sodium chloride or other alkaline or alkaline earth metal chloride. Also, to provide water necessary for the reaction, it has been tried to add a component such as activated carbon and silica gel for releasing water.
U.S. Pat. No. 5,721,187 has disclosed an oxygen absorber comprising an active carbon material layer and an oxygen absorbing layer comprising 15 to 80% by weight of a thermoplastic resin and 85 to 20% by weight of an oxygen absorbing agent. An amount of the active carbon material is 0.2 to 15% by weight relative to the oxygen absorbing agent. The oxygen absorber is easy to handle and excellent in oxygen absorbing performance. However, a rate of absorbing oxygen has been found not fast enough for a certain application
U.S. Pat. No. 6,586,514 has disclosed a composition comprising an oxidizable metal component, an electrolyte component and a non-electrolytic acidifying component. When the composition is blended with a flexible polymeric resin, it is possible to obtain good oxygen-absorbing performance with improved oxidation efficiency as compared with a rigid thermoplastic resin. The non-electrolytic acidifying component needs to be thermally stable under a condition of melt compounding with the polymeric resin, particularly for an extrusion coating application. Further, the efficiency of absorbing oxygen has not been high enough. Also, the composition includes three different components, resulting in complex material handling and manufacturing process.